The invention relates to a fuel cell system.
In the use of fuel cell systems, for instance as so-called APUs (auxiliary power units) and/or in vehicle drive systems as well as in stationary systems, the electrical energy management should be aware of the status of the fuel cell or fuel cell stack with regard to dynamics, performance, degradation, and/or minimum voltage. Especially in reformer systems, information is additionally required about the degradation and the dynamics of the gas generating unit. Only then can the availability and reliability of the system be assured.
Previously known systems meet these requirements only inadequately. For instance, U.S. Pat. No. 5,945,229 describes a fuel cell system in which the behavior of the current/voltage characteristic curve of the stack is ascertained via additional fuel cells at the stack inlet and the stack outlet. From this, the CO concentration in the hydrogen-rich anode gas is determined. In the event of a deviation from a reference behavior—that is, a set-point/actual-value comparison is made—protective measures are automatically tripped to avoid CO poisoning of the stack.